排序方式： 共有40条查询结果，搜索用时 31 毫秒
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Study of the transverse liquid flow paths in pine and spruce using scanning electron microscopy 总被引：4，自引：0，他引：4
Samples of pine (Pinus sylvestris) and spruce (Picea abies) were impregnated with a low-viscous epoxy resin using a vacuum process. The epoxy was cured in situ and the specimens sectioned. Deposits of the cured epoxy was then observed in the wood cavities using a scanning electron microscope. The investigation concentrated on tracing the transverse movements of a viscous liquid in the wood, and special attention was therefore given to the cross-field area between ray cells and longitudinal tracheids. A damage hypothesis is proposed based on the results obtained in the present investigation in combination with those from earlier studies on linseed oil-impregnated pine: In addition to the morphology of the bordered pits, viscous liquid flow in wood is dependent on damage that occurs during the impregnation procedure. For pine sapwood, liquid flow is enabled through disrupted window pit membranes, which divide the longitudinal tracheids and the ray parenchyma cells. A mechanism accounting for the reduced permeability of pine heartwood is believed to be deposits of higher-molecular-weight substances (extractives) in the ray parenchyma cells and on the cell walls. In spruce the thicker ray cells in combination with the smaller pits, which are connected to the longitudinal tracheids, reduce permeability considerably. 相似文献
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对杉松冷杉试材进行2种药剂(质量分数为0.5%和1.0%)、2种压缩率(5%和10%)、2种压缩方向(径向和弦向)、2种压缩次数(1和4次)的防腐剂辊压浸注和常温常压浸泡处理,测试和研究不同浸注方法对试材载药量、防治效力和真菌感染形态的影响。结果表明:辊压浸注法的载药量高于浸泡法,提高了133.33%~224.24%;前者防治效力比后者提高了25%以上,当辊压浸注工艺为压缩率10%、药剂质量分数1.0%、弦向压缩、压缩4次时,试材的防治效力达到最大值81.97%;可可球二孢真菌在空白样、浸泡法和辊压浸注法试材中的发展顺序呈现由旺盛到纤弱、由充满细胞腔到局部存在的态势,与试材表面和内部的宏观特征表现一致。 相似文献
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Modabber Ahmed Khan Wang Mingzhi Bu-Kug Lim Jong-Yoon Lee 《Journal of Wood Science》2008,54(2):158-161
To help address the physical, chemical, and biological degradation of agricultural soils resulting from indiscriminate use
of chemical fertilizers, we developed a slow-release fertilizer from waste paper and urea. This approach has the advantage
of a slow-release fertilizer in that it avoids surface runoff or leaching of nutrients, while providing an excellent medium
for the recycling of waste paper. The successful impregnation of urea into waste paper was confirmed by scanning electron
microscopy. This study also evaluated the release patterns of N from impregnated waste paper using a simulated soil solution
and distilled water as leaching solutions. The release patterns of N were examined in both static and continuous-flow conditions
for 720 h. Release of N from impregnated waste paper was found to be slow and steady, although the release rate of N was lower
in distilled water than soil solution under both conditions.
Part of this report was pesented at the Korean Society of Wood Science and Technology in Korea, April 2007, and the 3rd International
Conference on Environmental Science and Technology in Houston, USA, August 2007 相似文献
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An aqueous solution of phenolic resin was impregnated through drilled holes in wood, and we manufactured compressed wood with
the deformation fixed by the phenolic resin. The methods of impregnation used in this study were an in-liquid platen-pressing
method and a vacuum treatment. The effect of the drilled holes on solution retention was examined. Moreover, the control of
solution retention was examined under the application of compression drying. The impregnation of resin into the specimens
without drilled holes was insufficient, and the deformation could not be fixed. On the other hand, sufficient impregnation
was possible in the specimen with drilled holes, and the deformation fixation was observed. At the stage of compression when
the solution was squeezed out of the specimen, the solution retention of each specimen was accurately controlled in the specimens
with drilled holes. At the stage of compressive deformation and deformation fixation using a hot press, the specimens without
drilled holes could not be processed normally because swelling occurred. However, swelling did not occur in the specimens
with drilled holes.
Part of this report was presented at the 16th Annual Meeting of the Chubu Branch of the Japan Wood Research Society in Matsumoto,
November 2006 相似文献
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纳米CaCO3增强竹浆纤维/环氧树脂复合材料的动态力学性能 总被引：2，自引：2，他引：0
为探索碳酸钙(CaCO_3)无机颗粒界面增强机理,建立竹纤维表面微纳米颗粒的附载与界面增强技术的内在联系,该论文以竹浆纤维(bamboo pulp fiber,BPF)和环氧树脂为主要材料,采用纳米CaCO_3浸渍改性工艺,通过真空辅助树脂浸注技术制备BPF/环氧树脂复合材料,利用动态力学分析仪对其动态热机械性能和界面性能进行研究。结果表明:测试频率为单频(1Hz)时,在–20~120℃,纳米CaCO_3浸渍改性竹浆纤维(BPF treated by impregnation modification,IMBPF)增强环氧树脂复合材料的最大储能模量是BPF/环氧树脂复合材料的1.3倍;测试频率为多频(1,2,5,10和20 Hz)时,频率对BPF/环氧树脂复合材料和IMBPF/环氧树脂复合材料的影响规律相同,储能模量,损耗模量和损耗因子均随频率的增加而增加且逐渐向高温方向移动。BPF/环氧树脂复合材料和IMBPF/环氧树脂复合材料的玻璃化转变温度均随频率的增加而升高,而测试频率对损耗因子影响不大;IMBPF/环氧树脂复合材料的玻璃化转变表观活化能(369.0kJ/mol)低于BPF/环氧树脂复合材料(495.8 kJ/mol),但IMBPF/环氧树脂复合材料的频率和玻璃化转变温度倒数的相关性(决定系数0.987 6)优于对照样(决定系数0.965 9);在–20℃、40℃和100℃时,IMBPF/环氧树脂复合材料的储能模量对频率的依赖性高于对照样;纳米CaCO_3浸渍改性技术可改善复合材料的界面性能,从而为纳米增强复合材料的研究提供理论依据。 相似文献